Detection devices, methods and systems for gas phase materials

ABSTRACT

Sensor arrays, methods, and systems for detecting the presence of gas phase materials by the formation of films based on the gas phase material are disclosed. The gas phase materials preferentially deposit conductive films on receptor materials that can be detected. The invention may also provide for increased sensitivity to the deposition of conductive materials through the use of closely spaced conductive electrodes interconnected by lines of receptor material. Examples of gas phase materials that may be detected include RuO 4 , IrO 4  and RhO 4 .

This is a continuation of application Ser. No. 10/266,797, filed Oct. 8,2002, now U.S. Pat. No. 6,689,321, which is a continuation ofapplication Ser. No. 09/652,634, filed Aug. 31, 2000, now U.S. Pat. No.6,479,297, which are all incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the sensors for the detection ofselected materials. More particularly, the present invention pertains tosensors for the detection of gas phase materials.

BACKGROUND

In the fabrication of integrated circuits, various layers of the same ordifferent materials are used. For example, during the formation ofsemiconductor devices, such as dynamic random access memories (DRAMs),static random access memories (SRAMs), ferroelectric (FE) memories,etc., a variety of conductive and non-conductive materials are used toconstruct storage cell capacitors and also may be used ininterconnection structures, e.g., conductive layers of contact holes,vias, etc.

These materials are typically supplied in a gas phase conducive to theformation of a film on a surface. When supplied in the gas phase, manyof these materials may become toxic or otherwise harmful to health. As aresult, it may be important to monitor where these materials are foundand the concentrations in which they are found. Furthermore, because theeffects may be cumulative, i.e., repeated exposure to low levels of theselected materials may be additive, it may be important to providesensors and detection methods that are capable of measuring forcumulative exposure levels in addition to real-time exposure.

Semiconductor device manufacturing is one example of an environment inwhich the monitoring of exposure to potentially harmful materials can beadvantageous. For example, various metals, metallic compounds, metaloxides, etc. are used to manufacture various structures used insemiconductor devices. A number of these materials may pose health risksbased on exposure to the materials in the gas phase.

For example, ruthenium oxide and ruthenium have recently been employedin semiconductor devices because these materials are electricallyconductive, conducive to conformal deposition, and they are easilyetched. For example, the article entitled, “(Ba,Sr)TiO₃ Films Preparedby Liquid Source Chemical Vapor Deposition on Ru Electrodes,” byKawahara et al., Jpn. J. Appl. Phys., Vol. 35 (1996), Part 1, No. 9B(September 1996), pp. 4880-4885, describes the use of ruthenium andruthenium oxide for forming electrodes in conjunction with highdielectric constant materials. It is, however, known that gaseousruthenium tetraoxide (RuO₄) is toxic at very low levels, e.g., about 1part per billion (ppb). Monitoring of exposure to ruthenium tetraoxideis, therefore, both important due to its toxicity and difficult due tothe low exposure levels at which the toxicity becomes an issue.

For example, many detection systems or procedures for many different gasphase materials rely on chemically sensitive tapes. Stains are produceddue to chemical reactions occurring on the tapes in response to chemicalexposure and those stains can then be detected. Problems with such tapesmay, however, include sensitivity to different chemicals.

With respect to ruthenium tetraoxide, some useful chemically sensitivetapes are also sensitive to other chemicals such as oxidizing agents. Asa result, the tapes typically cannot be used to accurately detectexposure to ruthenium oxide. Other tapes may detect ruthenium oxide, butcould not be used to accurately detect at desired exposure levels.

SUMMARY OF THE INVENTION

The present invention provides sensors for and methods of detecting thepresence of gas phase materials by detecting the formation of filmsbased on the gas phase material. Advantageously, some gas phasematerials preferentially deposit on receptor materials. As a result,selective detection of those gas phase materials can be obtained bydetecting films deposited on the receptor materials. In addition toselectivity, the present invention may also provide for continuous filmdeposition on a receptor material at the minimum, or close to minimum,exposure levels.

Further advantages of the present invention are an increased sensitivityto the deposition of conductive materials through the use of closelyspaced conductive electrodes interconnected by lines of receptormaterial. The gas phase material preferentially deposits on the receptormaterial as compared to the surrounding substrate surface. Thatpreferential deposition may improve sensitivity of the sensor byreducing the areas on which the gas phase material will form conductivelayers.

In one aspect, the present invention provides for detection of gaseousruthenium oxide (RuO₄) which preferentially deposits on a variety ofsurfaces, e.g., polypropylene. The deposited film includes elementalruthenium (Ru) and/or ruthenium oxide (RuO₂) which exhibit relativelyhigh electrical conductivity. As a result, detection of gaseousruthenium oxide may be performed by monitoring electrical conductivityacross a detection surface. Exposure levels, may be determined based onthe increases in electrical conductivity.

Further advantages of the present invention may include reducedsensitivity to environmental contaminants because relatively fewenvironmental contaminants will deposit on any surface in the form of,e.g., an electrically conductive film. In addition, heating thedetection surface or otherwise treating the detection surface during orbefore use may further improve sensitivity to environmental contaminantsby reducing or eliminating deposition of environmental moisture and mostorganic materials.

Detection of the selected material or materials in the gaseous phase mayserve a variety of purposes including the detection of toxic/hazardousmaterials to insure proper industrial safety standards; to monitorreaction levels for process control; to determine the integrity ofcontainment systems; etc.

In one aspect, the present invention provides a sensor array fordetecting a gas phase material, the array including a substrate surface;at least one line of receptor material on the substrate surface, whereinthe gas phase material preferentially deposits on the receptor materialas compared to the substrate surface surrounding the receptor material;a serpentine electrode on the substrate surface, the serpentineelectrode including a plurality of U-shaped segments spaced along theline of receptor material and opening in alternating first and secondopposing directions along the line of receptor material; and a combelectrode on the substrate surface, the comb electrode including aplurality of tines, wherein at least some of the tines extend into atleast some of the U-shaped segments opening in the first direction, andfurther wherein at least some of the tines extending into the U-shapedsegments intersect the line of receptor material.

In another aspect, the present invention provides a sensor array fordetecting a gas phase material, the array including a substrate surface;at least two lines of receptor material on the substrate surface,wherein the gas phase material preferentially deposits on the receptormaterial as compared to the substrate surface surrounding the receptormaterial; a serpentine electrode on the substrate surface, theserpentine electrode including a plurality of U-shaped segments spacedalong the lines of receptor material and opening in alternating firstand second opposing directions along the lines of receptor material; anda comb electrode on the substrate surface, the comb electrode includinga plurality of tines, wherein at least some of the tines extend into atleast some of the U-shaped segments opening in the first direction, andfurther wherein at least some of the tines extending into the U-shapedsegments intersect the lines of receptor material.

In another aspect, the present invention provides a sensor array fordetecting a gas phase material, the array including a substrate surface;at least one line of receptor material on the substrate surface, whereinthe gas phase material preferentially deposits on the receptor materialas compared to the substrate surface surrounding the receptor material;a serpentine electrode on the substrate surface, the serpentineelectrode including a plurality of U-shaped segments spaced along theline of receptor material and opening in alternating first and secondopposing directions along the line of receptor material; a first combelectrode on the substrate surface, the first comb electrode including aplurality of tines, wherein at least some of the tines extend into atleast some of the U-shaped segments opening in the first direction, andfurther wherein at least some of the tines extending into the U-shapedsegments intersect the line of receptor material; and a second combelectrode on the substrate, the second comb electrode including aplurality of tines, wherein at least some of the tines extend into atleast some of the U-shaped segments opening in the second direction, andfurther wherein at least some of the tines of the second comb electrodeextending into the U-shaped segments intersect the line of receptormaterial.

In another aspect, the present invention provides a sensor array fordetecting a gas phase material, the array including a substrate surface;at least two lines of receptor material on the substrate surface,wherein the selected material preferentially deposits on the receptormaterial as compared to the substrate surface surrounding the receptormaterial; a serpentine electrode on the substrate surface, theserpentine electrode including a plurality of U-shaped segments spacedalong the lines of receptor material and opening in alternating firstand second opposing directions along the lines of receptor material; afirst comb electrode on the substrate surface, the first comb electrodeincluding a plurality of tines, wherein at least some of the tinesextend into at least some of the U-shaped segments opening in the firstdirection, and further wherein at least some of the tines extending intothe U-shaped segments intersect the lines of receptor material; and asecond comb electrode on the substrate, the second comb electrodeincluding a plurality of tines, wherein at least some of the tinesextend into at least some of the U-shaped segments opening in the seconddirection, and further wherein at least some of the tines of the secondcomb electrode extending into the U-shaped segments intersect the linesof receptor material.

In another aspect, the present invention provides a method of detectinga gas phase material by providing a sensor array including a substratesurface; at least one line of receptor material on the substratesurface, wherein the gas phase material preferentially deposits on thereceptor material as compared to the substrate surface surrounding thereceptor material; a serpentine electrode on the substrate surface, theserpentine electrode including a plurality of U-shaped segments spacedalong the line of receptor material and opening in alternating first andsecond opposing directions along the line of receptor material; and acomb electrode on the substrate surface, the comb electrode including aplurality of tines, wherein at least some of the tines extend into atleast some of the U-shaped segments opening in the first direction, andfurther wherein at least some of the tines extending into the U-shapedsegments intersect the line of receptor material. The method alsoincludes exposing the sensor array to the gas phase material andmonitoring electrical conductivity between the serpentine electrode andthe comb electrode.

In another aspect, the present invention provides a method of detectinga gas phase material by providing a sensor array including a substratesurface; at least two lines of receptor material on the substratesurface, wherein the gas phase material preferentially deposits on thereceptor material as compared to the substrate surface surrounding thereceptor material; a serpentine electrode on the substrate surface, theserpentine electrode including a plurality of U-shaped segments spacedalong the lines of receptor material and opening in alternating firstand second opposing directions along the lines of receptor material; anda comb electrode on the substrate surface, the comb electrode includinga plurality of tines, wherein at least some of the tines extend into atleast some of the U-shaped segments opening in the first direction, andfurther wherein at least some of the tines extending into the U-shapedsegments intersect the lines of receptor material a substrate surface.The method also includes exposing the sensor array to the gas phasematerial and monitoring electrical conductivity between the serpentineelectrode and the comb electrode.

In another aspect, the present invention provides a method of detectinga gas phase material by providing a sensor array including a substratesurface; at least one line of receptor material on the substratesurface, wherein the gas phase material preferentially deposits on thereceptor material as compared to the substrate surface surrounding thereceptor material; a continuous serpentine electrode on the substratesurface, the serpentine electrode including a plurality of U-shapedsegments spaced along the line of receptor material and opening inalternating first and second opposing directions along the line ofreceptor material; a first comb electrode on the substrate surface, thefirst comb electrode including a plurality of tines, wherein at leastsome of the tines extend into at least some of the U-shaped segmentsopening in the first direction, and further wherein at least some of thetines extending into the U-shaped segments intersect the line ofreceptor material; and a second comb electrode on the substrate, thesecond comb electrode including a plurality of tines, wherein at leastsome of the tines extend into at least some of the U-shaped segmentsopening in the second direction, and further wherein at least some ofthe tines of the second comb electrode extending into the U-shapedsegments intersect the line of receptor material. The method alsoincludes exposing the sensor array to the gas phase material andmonitoring electrical conductivity between the serpentine electrode andat least one of the first and second comb electrodes.

In another aspect, the present invention provides a method of detectinga gas phase material by providing a sensor array including a substratesurface; at least two lines of receptor material on the substratesurface, wherein the selected material preferentially deposits on thereceptor material as compared to the substrate surface surrounding thereceptor material; a serpentine electrode on the substrate surface, theserpentine electrode including a plurality of U-shaped segments spacedalong the lines of receptor material and opening in alternating firstand second opposing directions along the lines of receptor material; afirst comb electrode on the substrate surface, the first comb electrodeincluding a plurality of tines, wherein at least some of the tinesextend into at least some of the U-shaped segments opening in the firstdirection, and further wherein at least some of the tines extending intothe U-shaped segments intersect the lines of receptor material; and asecond comb electrode on the substrate, the second comb electrodeincluding a plurality of tines, wherein at least some of the tinesextend into at least some of the U-shaped segments opening in the seconddirection, and further wherein at least some of the tines of the secondcomb electrode extending into the U-shaped segments intersect the linesof receptor material. The method further includes exposing the sensorarray to the gas phase material and monitoring electrical conductivitybetween the serpentine electrode and at least one of the first andsecond comb electrodes.

In another aspect, the present invention provides a system for detectinga gas phase material, the system including a sensor array with asubstrate surface; at least one line of receptor material on thesubstrate surface, wherein the gas phase material preferentiallydeposits on the receptor material as compared to the substrate surfacesurrounding the receptor material; a serpentine electrode on thesubstrate surface, the serpentine electrode including a plurality ofU-shaped segments spaced along the line of receptor material and openingin alternating first and second opposing directions along the line ofreceptor material; and a comb electrode on the substrate surface, thecomb electrode including a plurality of tines, wherein at least some ofthe tines extend into at least some of the U-shaped segments opening inthe first direction, and further wherein at least some of the tinesextending into the U-shaped segments intersect the line of receptormaterial. The system further includes a detector in electricalcommunication with the serpentine electrode and the comb electrode.

In another aspect, the present invention provides a system for detectinga gas phase material, the system including a sensor array with asubstrate surface; at least two lines of receptor material on thesubstrate surface, wherein the gas phase material preferentiallydeposits on the receptor material as compared to the substrate surfacesurrounding the receptor material; a serpentine electrode on thesubstrate surface, the serpentine electrode including a plurality ofU-shaped segments spaced along the lines of receptor material andopening in alternating first and second opposing directions along thelines of receptor material; and a comb electrode on the substratesurface, the comb electrode including a plurality of tines, wherein atleast some of the tines extend into at least some of the U-shapedsegments opening in the first direction, and further wherein at leastsome of the tines extending into the U-shaped segments intersect thelines of receptor material a substrate surface. The system furtherincludes a detector in electrical communication with the serpentineelectrode and the comb electrode.

In another aspect, the present invention includes a system for detectinga gas phase material, the system including a sensor array with asubstrate surface; at least one line of receptor material on thesubstrate surface, wherein the gas phase material preferentiallydeposits on the receptor material as compared to the substrate surfacesurrounding the receptor material; a serpentine electrode on thesubstrate surface, the serpentine electrode including a plurality ofU-shaped segments spaced along the line of receptor material and openingin alternating first and second opposing directions along the line ofreceptor material; a first comb electrode on the substrate surface, thefirst comb electrode including a plurality of tines, wherein at leastsome of the tines extend into at least some of the U-shaped segmentsopening in the first direction, and further wherein at least some of thetines extending into the U-shaped segments intersect the line ofreceptor material; and a second comb electrode on the substrate, thesecond comb electrode including a plurality of tines, wherein at leastsome of the tines extend into at least some of the U-shaped segmentsopening in the second direction, and further wherein at least some ofthe tines of the second comb electrode extending into the U-shapedsegments intersect the line of receptor material. The system furtherincludes a detector in electrical communication with the serpentineelectrode, the first comb electrode and the second comb electrode.

In another aspect, the present invention provides a system for detectinga gas phase material, the system including a sensor array with asubstrate surface; at least two lines of receptor material on thesubstrate surface, wherein the selected material preferentially depositson the receptor material as compared to the substrate surfacesurrounding the receptor material; a serpentine electrode on thesubstrate surface, the serpentine electrode including a plurality ofU-shaped segments spaced along the lines of receptor material andopening in alternating first and second opposing directions along thelines of receptor material; a first comb electrode on the substratesurface, the first comb electrode including a plurality of tines,wherein at least some of the tines extend into at least some of theU-shaped segments opening in the first direction, and further wherein atleast some of the tines extending into the U-shaped segments intersectthe lines of receptor material; and a second comb electrode on thesubstrate, the second comb electrode including a plurality of tines,wherein at least some of the tines extend into at least some of theU-shaped segments opening in the second direction, and further whereinat least some of the tines of the second comb electrode extending intothe U-shaped segments intersect the lines of receptor material. Thesystem further includes a detector in electrical communication with theserpentine electrode, the first comb electrode and the second combelectrode.

These and other features and advantages of the present invention aredescribed below with respect to illustrative embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood from reading thefollowing description of illustrative embodiments with reference to theattached drawings, wherein below:

FIG. 1 illustrates one sensor array according to the present invention.

FIG. 2 is a cross-sectional view of the sensor array during onemanufacturing process.

FIG. 3 is a cross-sectional view illustrating the relationship betweenthe substrate, receptor lines and electrodes on preferred sensor arraysaccording to the present invention.

FIG. 4 illustrates another sensor array according to the presentinvention.

FIG. 5 illustrates another sensor array according to the presentinvention.

FIG. 6 illustrates another sensor array according to the presentinvention.

FIG. 7 is a block diagram of a system using a sensor array to detect gasphase materials in accordance with the present invention

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS OF THE INVENTION

The present invention provides devices and methods for the monitoring ofgas phase material levels by detecting films formed from the gas phasematerials on receptor materials. One example of an industry using gasphase materials is in the production of semiconductor and othermicro-scale devices. Processing steps such as wet etching, dry etching,chemical vapor deposition, etc., may often use or produce gas phasematerials that may be, e.g., toxic, corrosive, irritants, etc. Detectionof the gas phase materials may be desirable for safety, environmental,or process control purposes. Examples of gas phase materials that may bedetected include, but are not limited to, RuO₄, IrO₄ and RhO₄.

Some methods and devices for detecting gas phase materials including,e.g., ruthenium, is described in U.S. patent application Ser. No.09/388,286, filed on Sep. 1, 1999, entitled DETECTION OF GAS PHASEMATERIALS. The present invention provides further advantages.

The present invention capitalizes on the tendencies of the gas phasematerials to deposit or form films or coatings on receptor materials. Insome instances, the gas phase materials will preferentially deposit onreceptor materials that have a particular structure. By relying onpreferential deposition tendencies, the present invention offersadvantages in monitoring for the materials. For example, continuous filmdeposition of the gas phase materials on the receptor material may beobtained at minimum, or close to minimum, exposure levels.

As formed on the receptor materials as a result of exposure to the gasphase material, the film may consist essentially of the gas phasematerial, the film may include one or more constituents in the gas phasematerial, or the film may be formed of the gas phase material or one ormore constituents thereof in addition with other materials, in e.g., amatrix, dispersion, etc.

It may be preferred that, as deposited, the gas phase material ormaterials form an electrically conductive film or coating on a receptormaterial. By detecting changes in the electrical properties (e.g.,conductivity, capacitance, etc.) between at least two electrodes on thereceptor material, the present invention provides the ability to detectthe presence of the gas phase materials.

Typically, deposition rate will be dependent on a variety of factorsincluding, but not limited to the concentration of the selected materialin the gaseous state, the properties of the receptor material (e.g.,temperature, morphology, etc.), and the environment in which thereceptor material is located (e.g., temperature, pressure, etc.). Othervariables affecting deposition rate may include deposition-enhancingfactors, such as laser-assisted deposition, plasma generation, etc.Regardless of the variables in deposition rate, however, it is preferredthat the rate of change in conductivity correlate with exposure levels.

To further enhance sensitivity to the gas phase material being detected,the receptor material is provided in selected areas on a substratesurface. Conductive electrodes are then located over the receptormaterial. The gas phase material preferentially deposits on the receptormaterial as compared to the substrate surface surrounding the receptormaterial. As a result, sensitivity is enhanced because the gas phasematerial deposited on the receptor material is concentrated on thereceptor material, thereby exhibiting faster increases in conductivityas compared to sensors in which the entire surface between electrodesreceives a deposited gas phase material.

In addition to providing receptor material in only selected areas on thesubstrate surface, sensitivity is further enhanced in connection withthe present invention by providing at least two electrodes thatintersect the receptor material in multiple locations forming a sensorarray. The sensor array thus formed provides an increased number ofpotential conductive paths between electrodes that can be formed bydeposition of the gas phase material. As the potential conductive pathsare connected during deposition of the gas phase material on thereceptor material, the electrical conductivity between the electrodes isincreased. Monitoring for that increased electrical conductivity canprovide for detection of the gas phase material.

Exemplary embodiments of sensor arrays and systems using the arrays aredescribed below in connection with the figures.

FIG. 1 is a schematic diagram of one sensor array 10 according to thepresent invention. The sensor array 10 includes three lines 20 a, 20 b,20 c (collectively referred to herein as lines 20) of receptor materialon a substrate surface 12. Although three lines 20 are illustrated, itshould be understood that only one line, only two lines, or more thanthree lines could be provided in a sensor array 10 according to thepresent invention.

It may be preferred that the lines 20 of receptor material do notintersect with each other. The illustrated lines 20 may also be,optionally, straight, parallel to each other, and/or of consistent widthalong their length.

The array 10 also includes a serpentine electrode 30, first combelectrode 40, and an optional second comb electrode 50. The serpentineelectrode 30 includes U-shaped segments spaced along the lines 20 ofreceptor material, the U-shaped segments opening in alternating firstand second opposing directions on opposite sides of the lines 20 ofreceptor material. In FIG. 1, those opposing directions are towards thetop of the sheet and bottom of the sheet. One of the U-shaped segmentsin serpentine electrode 30 is formed, in the illustrated embodiment, bylegs 32 and 34, which are connected by a base segment 36. Other shapesmay be envisioned, such as a U-shape with a rounded base segment 36.

The serpentine electrode 30 may include, in the illustrated embodiment,a connection pad 38 to which a sensor can be connected as will bedescribed in more detail below.

A first comb electrode 40 is also illustrated in FIG. 1 as a part of thearray 10. The comb electrode 40 includes tines 42 extending into theU-shaped segments formed by the serpentine electrode 30. The tines 42intersect the lines 20 of receptor material as they pass through theU-shaped segments of the serpentine electrode 30. The tines 42 areconnected by a spine 44 that leads out, in the illustrated embodiment,to an optional connection pad 48 for connection to a sensor.

Also illustrated in FIG. 1 is an optional second comb electrode 50including tines 52 connected to a spine 54 that leads out to an optionalconnection pad 58. The tines 52 of the second comb electrode 50 extendinto the U-shaped segments of the serpentine electrode 30 that open inthe opposite direction from those in which tines 42 of the first combelectrode 40 are located.

The serpentine electrode 30, and comb electrodes 40 and 50 are separatedfrom each other in the illustrated array 10 by the lines 20 of receptormaterial and the substrate surface 12 that surrounds the lines 20 ofreceptor material. Both the lines 20 of receptor material and thesubstrate surface 12 preferably electrically isolates the serpentineelectrode 30 from the comb electrodes 40 and 50 such that, e.g., currentis prevented from flowing between the serpentine electrode 30 and thecomb electrodes 40 and 50. Alternatively, the lines 20 of receptormaterial and the substrate surface 12 may provide low level conductivitybetween the serpentine electrode 30 and either or both of the combelectrodes 40 and 50, with the conductivity increasing as a conductivefilm is formed on the lines 20 of receptor material from the gas phasematerial.

Selection of the receptor material used in lines 20 relative to thesubstrate surface 12 is influenced by the desired preferential nature ofthe deposition process. The receptor material should preferentiallyattract deposition of the gas phase material to be detected relative toany of the other materials exposed on the surface of the array 10 toenhance sensitivity of the detection. It may further be preferred thatthe substrate surface 12 and/or electrodes 30, 40 and 50 be provided ofmaterials that allow for relatively free migration of the gas phasematerial deposited thereon to the receptor material forming lines 20. Asa result, film formation of the gas phase material on the lines 20 ofreceptor material may be enhanced. That enhanced film formation mayimprove detection sensitivity. Illustrative examples of suitablereceptor materials on which gaseous ruthenium oxide preferentiallydeposits include, but are not limited to, polypropylene, fluoropolymers,1,1,1,3,3,3-hexamethyldisiloxane (HMDS) coated surfaces, amorphouscarbon, parylene, etc.

The substrate surface 12 surrounding the receptor material in lines 20may include a variety of materials that preferably exhibit a tendency toallow relatively free migration of the gas phase material depositedthereon (relative to the receptor materials in lines 20). Examples ofsuitable materials include, but are not limited to, e.g., inorganicmaterials such as quartz, silicon oxide, silicon nitride,borophosphosilicate glass, etc.

Alternatively, deposition of the gas phase material on the receptormaterial and/or substrate surface 12 may be affected by surfacemorphology, e.g., whether the surfaces are relatively smooth or rough. Arough surface may be structured by, e.g., molding, or randomly roughenedby e.g., sandblasting, chemical etching, etc.

In addition to the materials selected for the sensor array 10, thedistances between the various features on the array 10, e.g., betweenthe serpentine electrode 30 and the comb electrodes 40 and 50, may beused to control the sensitivity of the detector 10 to a particular gasphase material. Other dimensions that may affect sensitivity of thesensor array 10 include the widths of the various features on the array10. Factors affecting the selection of an appropriate dimensions mayinclude, but are not limited to: resistivity of the depositedfilm/coating (from the gas phase material), resistivity of the receptormaterial before deposition, ambient conditions (humidity, temperature,etc.), temperature, etc.

In use, the sensor array 10 is connected to a detector (not shown inFIG. 1) that is capable of detecting a change in conductivity betweenthe serpentine electrode 30 and one or both of the comb electrodes 40and 50 across the lines 20 of receptor material as a result ofdeposition of one or more gas phase materials in the form of a film orcoating on the receptor material. It is preferred that low leveldepositions of a conductive film on the lines 20 of receptor materialcan produce a finite and accurately measurable change in current flowbetween the electrodes.

Turning now to FIG. 2, it may be desirable to manufacture the sensorarray 10 by first depositing a layer 14 of the receptor material on thesubstrate surface 12. That layer 14 can then be patterned using knownprocesses to form, e.g., lines 20 of receptor material as seen in FIG.1. Following formation of the lines 20 from receptor material 14, theconductive electrode material 16 used to form the electrodes can beprovided over the receptor material in the line 20 as illustrated inFIG. 3.

Although one illustrative sensor array 10 is depicted in FIG. 1,alternative array designs are possible. One such alternative is depictedin FIG. 4, in which a single comb electrode 140 is provided with tines142 that extend into the U-shaped segments of the serpentine electrode130 opening to both sides of the receptor material lines 120 a, 120 b,120 c (collectively referred to as lines 120). As a result, the spine144 of the comb electrode 140 extends around a significant portion ofthe serpentine electrode 130. The tines 142 intersect the lines 120 ofreceptor material along with the serpentine electrode 130. Both theillustrated serpentine electrode 130 and the illustrated comb electrode140 terminate in optional connection pads 138 and 148, respectively, forconnection to a detector (not shown).

Another alternative array design is depicted in FIG. 5 in which thereceptor material lines 220 a and 220 b (collectively referred to aslines 220) are provide in a generally circular shape. The array includesa serpentine electrode 230 that also includes U-shaped segments openingtowards both opposing sides of the lines 220. The array also includes acomb electrode 240 with tines 242 extending into the U-shaped segmentsfrom the within the generally circular lines 220, with the tines 242intersecting with the lines 220 in those U-shaped segments. A secondcomb electrode 250 is also seen in FIG. 5 that includes tines 252extending into the U-shaped segments that open outwardly. The tines 252are connected by a spine 254 that extends about the exterior of theserpentine electrode 230.

FIG. 6 depicts another illustrative sensor array design in which asinusoidal serpentine electrode 330 extends along receptor materiallines 320 a and 320 b (collectively referred to as lines 320). TheU-shaped segments of the serpentine electrode 330 are, in thisembodiment, provided by the sinusoidal wave pattern. The array includesa pair of comb electrodes 340 and 350 that conform to the shape of thesinusoidal serpentine electrode 330 and that also cross the receptormaterial lines 320. One variation depicted in this array design is thatthe tines 342 and 352 of the comb electrodes 340 and 350 (respectively)may be provided as portions of a continuous line forming the entireelectrode 340 or 350, rather than terminating line segments connected toa spine as depicted in FIGS. 1-5.

One illustrative method of detecting a gas phase material will now bedescribed with respect to ruthenium oxide, although it should beunderstood that the methods of the present invention may be used todetect a variety of other gas phase materials. Other gas phase materialsthat could be detected by the devices and methods of the presentinvention include any gas phase material that deposits on a receptormaterial in the form of an electrically conductive film or coating.

It will be understood that the composition of the gas phase materialwill typically correspond to the composition of the film or coating, butthat the exact compositions may be different. For example, gas phaseruthenium tetraoxide (RuO₄) can be detected based on a film or coatingincluding elemental ruthenium (Ru) and/or ruthenium dioxide (RuO₂), bothof which are electrically conductive. Examples of other gas phasematerials that can be detected according to the principles of thepresent invention include, but are not limited to, IrO₄ and RhO₄.

Ruthenium tetraoxide can be deposited by chemical vapor deposition (CVD)which is defined as the formation of a nonvolatile solid film on asubstrate by reaction of vapor phase reactants, i.e., reacting gases,that contain desired components.

In a CVD process, the reacting gases are introduced into the reactionchamber. The gas is decomposed and reacted at a heated wafer surface toform the desired layer. Chemical vapor deposition is just one process ofproviding thin layers on substrate assemblies and other surfaces, suchas films of elemental metals or compounds, e.g., platinum, ruthenium,ruthenium oxide, etc. The CVD process may be enhanced by various relatedtechniques such as plasma assistance, photo assistance, laserassistance, as well as other techniques.

The CVD process for depositing ruthenium and/or ruthenium oxide isconducted with a ruthenium containing precursor being delivered to areaction chamber. Diluent gases may also optionally be provided to thereaction chamber. One skilled in the art will recognize that the mannerin which the gases are introduced into the reaction chamber may includeone of various techniques.

Gas products contained within the CVD system are potentially harmful topersonnel located around the equipment. The present invention providesmethods of detecting the escape of the selected materials based on theirdeposition onto a detection surface and the resulting change in theconductivity of the detection surface.

Referring to FIG. 7, a sensor 400 according to the present invention islocated in proximity to a CVD system 460 in which ruthenium or rutheniumor ruthenium oxide is to be deposited. In some systems, ruthenium oxidemay be formed in the CVD system 460 if it is supplied with oxygen inaddition to ruthenium for the purpose of forming ruthenium oxide on asubstrate.

A sensor 400 according to the present invention, however, may be able todetect gaseous ruthenium oxide that escapes from the system 460. Thesensor 400 includes a sensor array 410 and a detector 402 capable ofdetecting a change in the conductivity between the electrodes on thesensor array 410. The detector 402 preferably includes an electricalcircuit capable of detecting the conductivity change between electrodeson the sensor array 410 through the film formed on the receptormaterials. If the conductivity reaches a predetermined limit, an alarm404 can be activated.

If gas phase ruthenium tetraoxide escapes from the CVD system 460, itwill typically form ruthenium oxide by oxidation reduction upon contactwith the sensor array 410. The deposited film or coating is electricallyconductive and, as a result, a change in the conductivity within thearray 410 can be used to indicate the presence of ruthenium oxide gas inthe area of the sensor 400, thereby alerting personnel in the area orthose monitoring an unoccupied area of a potential hazard.

It may be desirable to, e.g., heat the sensor array 410 above theambient temperature using a heater 406 to potentially enhancesensitivity of the sensor array 410. For example, heating the sensorarray 410 may limit deposition of ambient moisture vapor or organicmaterials present in the atmosphere around the sensor array 410. In thecase of ruthenium oxide detection, heating the detection surface up toabout 100° C. may be useful to enhance detection.

The heater 406 should be capable of providing thermal energy to thesensor array 410 by any suitable manner including conduction,convection, and/or radiation. In addition, the heater 406 may be anelectrical resistance heater, operate using RF excitation, infraredradiation, etc.

It may also be desirable to subject the array 410 to other forms ofenergy, in addition to or in place of heating, to enhance detectionsensitivity. Examples of suitable energy forms include, but are notlimited to electromagnetic radiation (visible or not), magnetic fields,etc.

All patents and references cited herein are incorporated in theirentirety as if each were incorporated separately. This invention hasbeen described with reference to illustrative embodiments and is notmeant to be construed in a limiting sense. Various modifications of theillustrative embodiments, as well as additional embodiments of theinvention, will be apparent to persons skilled in the art upon referenceto this description. It is therefore contemplated that the appendedclaims will cover any such modifications or embodiments that may fallwithin the scope of the present invention as defined by the accompanyingclaims.

1. A sensor array for detecting a metallic compound in a gas phasematerial, the array comprising: a substrate surface; at least one lineof receptor material attached to the substrate surface, wherein ametallic compound in a gas phase material preferentially deposits on thereceptor material as compared to the substrate surface surrounding thereceptor material; and at least two electrodes attached to the substratesurface, wherein the at least two electrodes intersect the at least oneline of receptor material in multiple locations such that a plurality ofpotential conductive paths are created between the at least twoelectrodes are created by the at least one line of receptor material. 2.A sensor array according to claim 1, wherein the receptor material islocated between the substrate surface and the at least two electrodeswhere the at least one line of receptor material and the at least twoelectrodes intersect.
 3. A sensor array according to claim 1, whereinthe metallic compound in the gas phase material preferentially depositson the receptor material as compared to the at least two electrodes. 4.A sensor array for detecting a metallic compound in a gas phasematerial, the array comprising: a substrate surface; at least two linesof receptor material attached to the substrate surface, wherein ametallic compound in a gas phase material preferentially deposits on thereceptor material as compared to the substrate surface surrounding thereceptor material; and at least two electrodes attached to the substratesurface, wherein the at least two electrodes intersect the at least twolines of receptor material in multiple locations such that a pluralityof potential conductive paths are created between the at least twoelectrodes are created by the at least two lines of receptor material.5. A sensor array according to claim 4, wherein according to the atleast two lines of receptor material do not intersect each other.
 6. Asensor array according to claim 4, wherein the receptor material islocated between the substrate surface and the at least two electrodeswhere the at least two lines of receptor material and the at least twoelectrodes intersect.
 7. A sensor array according to claim 4, whereinthe metallic compound in the gas phase material preferentially depositson the receptor material as compared to the at least two electrodes. 8.A method of detecting a metallic compound in a gas phase material, themethod comprising: providing a sensor array comprising: a substratesurface; at least one line of receptor material attached to thesubstrate surface, wherein a metallic compound in a gas phase materialpreferentially deposits on the receptor material as compared to thesubstrate surface surrounding the receptor material; and at least twoelectrodes attached to the substrate surface, wherein the at least twoelectrodes intersect the at least one line of receptor material inmultiple locations such that a plurality of potential conductive pathsare created between the at least two electrodes are created by the atleast one line of receptor material; exposing the sensor array to thegas phase material that comprises the metallic compound; and monitoringelectrical conductivity between the at least two electrodes.
 9. A methodaccording to claim 8, further comprising activating an alarm when theelectrical conductivity between the at least two electrodes reaches apredetermined limit.
 10. A method according to claim 8, wherein thereceptor material is located between the substrate surface and the atleast two electrodes where the at least one line of receptor materialand the at least two electrodes intersect.
 11. A method according toclaim 8, wherein the metallic compound in the gas phase materialpreferentially deposits on the receptor material as compared to the atleast two electrodes.
 12. A method of detecting a metallic compound in agas phase material, the method comprising: providing a sensor arraycomprising: a substrate surface; at least two lines of receptor materialattached to the substrate surface, wherein a metallic compound in a gasphase material preferentially deposits on the receptor material ascompared to the substrate surface surrounding the receptor material; andat least two electrodes attached to the substrate surface, wherein theat least two electrodes intersect the at least two lines of receptormaterial in multiple locations such that a plurality of potentialconductive paths are created between the at least two electrodes arecreated by the at least two lines of receptor material; exposing thesensor array to the gas phase material that comprises the metalliccompound; and monitoring electrical conductivity between the at leasttwo electrodes.
 13. A method according to claim 12, further comprisingactivating an alarm when the electrical conductivity between the atleast two electrodes reaches a predetermined limit.
 14. A methodaccording to claim 12, wherein the at least two lines of receptormaterial do not intersect each other.
 15. A method according to claim12, wherein the receptor material is located between the substratesurface and the at least two electrodes where the at least one line ofreceptor material and the at least two electrodes intersect.
 16. Amethod according to claim 12, wherein the metallic compound in the gasphase material preferentially deposits on the receptor material ascompared to the at least two electrodes.
 17. A system for detecting ametallic compound in a gas phase material, the system comprising: asensor array comprising: a substrate surface; at least one line ofreceptor material attached to the substrate surface, wherein a metalliccompound in a gas phase material preferentially deposits on the receptormaterial as compared to the substrate surface surrounding the receptormaterial; and at least two electrodes attached to the substrate surface,wherein the at least two electrodes intersect the at least one line ofreceptor material in multiple locations such that a plurality ofpotential conductive paths are created between the at least twoelectrodes are created by the at least one line of receptor material;and a detector in electrical communication with the at least twoelectrodes.
 18. A system according to claim 17, wherein the receptormaterial is located between the substrate surface and the at least twoelectrodes where the at least one line of receptor material and the atleast two electrodes intersect.
 19. A system according to claim 17,wherein the metallic compound in the gas phase material preferentiallydeposits on the receptor material as compared to the at least twoelectrodes.
 20. A system for detecting a metallic compound in a gasphase material, the system comprising: a sensor array comprising: asubstrate surface; at least two lines of receptor material attached tothe substrate surface, wherein a metallic compound in a gas phasematerial preferentially deposits on the receptor material as compared tothe substrate surface surrounding the receptor material; and at leasttwo electrodes attached to the substrate surface, wherein the at leasttwo electrodes intersect the at least two lines of receptor material inmultiple locations such that a plurality of potential conductive pathsare created between the at least two electrodes are created by the atleast two lines of receptor material; and a detector in electricalcommunication with the at least two electrodes.
 21. A system accordingto claim 20, wherein the at least two lines of receptor material do notintersect each other.
 22. A system according to claim 20, wherein thereceptor material is located between the substrate surface and the atleast two electrodes where the at least two lines of receptor materialand the at least two electrodes intersect.
 23. A system according toclaim 20, wherein the metallic compound in the gas phase materialpreferentially deposits on the receptor material as compared to the atleast two electrodes.
 24. A sensor array for detecting a rutheniumcompound in a gas phase material, the array comprising: a substratesurface; at least one line of receptor material attached to thesubstrate surface, wherein a ruthenium compound in a gas phase materialpreferentially deposits on the receptor material as compared to thesubstrate surface surrounding the receptor material; and at least twoelectrodes attached to the substrate surface, wherein the at least twoelectrodes intersect the at least one line of receptor material inmultiple locations such that a plurality of potential conductive pathsare created between the at least two electrodes are created by the atleast one line of receptor material.
 25. A sensor array according toclaim 24, wherein the receptor material is located between the substratesurface and the at least two electrodes where the at least one line ofreceptor material and the at least two electrodes intersect.
 26. Asensor array according to claim 24, wherein the ruthenium compound inthe gas phase material preferentially deposits on the receptor materialas compared to the at least two electrodes.
 27. A sensor array fordetecting a ruthenium compound in a gas phase material, the arraycomprising: a substrate surface; at least two lines of receptor materialattached to the substrate surface, wherein a ruthenium compound in a gasphase material preferentially deposits on the receptor material ascompared to the substrate surface surrounding the receptor material; andat least two electrodes attached to the substrate surface, wherein theat least two electrodes intersect the at least two lines of receptormaterial in multiple locations such that a plurality of potentialconductive paths are created between the at least two electrodes arecreated by the at least two lines of receptor material.
 28. A sensorarray according to claim 27, wherein the at least two lines of receptormaterial do not intersect each other.
 29. A sensor array according oclaim 27, wherein the receptor material is located between the substratesurface and the at least two electrodes where the at least two lines ofreceptor material and the at least two electrodes intersect.
 30. Asensor array according to claim 27, wherein the ruthenium compound inthe gas phase material preferentially deposits on the receptor materialas compared to the at least two electrodes.
 31. A method of detecting aruthenium compound in a gas phase material, the method comprising:providing a sensor array comprising: a substrate surface; at least oneline of receptor material attached to the substrate surface, wherein aruthenium compound in a gas phase material preferentially deposits onthe receptor material as compared to the substrate surface surroundingthe receptor material; and at least two electrodes attached to thesubstrate surface, wherein the at least two electrodes intersect the atleast one line of receptor material in multiple locations such that aplurality of potential conductive paths are created between the at leasttwo electrodes are created by the at least one line of receptormaterial; exposing the sensor array to the gas phase material thatcomprises the ruthenium compound; and monitoring electrical conductivitybetween the at least two electrodes.
 32. A method according to claim 31,further comprising activating an alarm when the electrical conductivitybetween the at least two electrodes reaches a predetermined limit. 33.Method according to claim 31, wherein the receptor material is locatedbetween the substrate surface and the at least two electrodes where theat least one line of receptor material and the at least two electrodesintersect.
 34. A method according to claim 31, wherein the rutheniumcompound in the gas phase material preferentially deposits on thereceptor material as compared to the at least two electrodes.
 35. Amethod of detecting a ruthenium compound in a gas phase material, themethod comprising: providing a sensor array comprising: a substratesurface; at least two lines of receptor material attached to thesubstrate surface, wherein a ruthenium compound in a gas phase materialpreferentially deposits on the receptor material as compared to thesubstrate surface surrounding the receptor material; and at least twoelectrodes attached to the substrate surface, wherein the at least twoelectrodes intersect the at least two lines of receptor material inmultiple locations such that a plurality of potential conductive pathsare created between the at least two electrodes are created by the atleast two lines of receptor material; exposing the sensor array to thegas phase material that comprises the ruthenium compound; and monitoringelectrical conductivity between the at least two electrodes.
 36. Amethod according to claim 35, further comprising activating an alarmwhen the electrical conductivity between the at least two electrodesreaches a predetermined limit.
 37. A method according to claim 35,wherein the at least two lines of receptor material do not intersecteach other.
 38. A method according to claim 35, wherein the receptormaterial is located between the substrate surface and the at least twoelectrodes where the at least one line of receptor material and the atleast two electrodes intersect.
 39. A method according to claim 35,wherein the ruthenium compound in the gas phase material preferentiallydeposits on the receptor material as compared to the at least twoelectrodes.
 40. A system for detecting a ruthenium compound in a gasphase material, the system comprising: a sensor array comprising: asubstrate surface; at least one line of receptor material attached tothe substrate surface, wherein a ruthenium compound in a gas phasematerial preferentially deposits on the receptor material as compared tothe substrate surface surrounding the receptor material; and at leasttwo electrodes attached to the substrate surface, wherein the at leasttwo electrodes intersect the at least one line of receptor material inmultiple locations such that a plurality of potential conductive pathsare created between the at least two electrodes are created by the atleast one line of receptor material; and a detector in electricalcommunication with the at least two electrodes.
 41. A system accordingto claim 40, wherein the receptor material is located between thesubstrate surface and the at least two electrodes where the at least oneline of receptor material and the at least two electrodes intersect. 42.A system according to claim 40, wherein the ruthenium compound in thegas phase material preferentially deposits on the receptor material ascompared to the at least two electrodes.
 43. A system for detecting aruthenium compound in a gas phase material, the system comprising: asensor array comprising: a substrate surface; at least two lines ofreceptor material attached to the substrate surface, wherein a rutheniumcompound in a gas phase material preferentially deposits on the receptormaterial as compared to the substrate surface surrounding the receptormaterial; and at least two electrodes attached to the substrate surface,wherein the at least two electrodes intersect the at least two lines ofreceptor material in multiple locations such that a plurality ofpotential conductive paths are created between the at least twoelectrodes are created by the at least two lines of receptor material;and a detector in electrical communication with the at least twoelectrodes.
 44. A system according to claim 43, wherein the at least twolines of receptor material do not intersect each other.
 45. A systemaccording to claim 43, wherein the receptor material is located betweenthe substrate surface and the at least two electrodes where the at leasttwo lines of receptor material and the at least two electrodesintersect.
 46. A system according to claim 43, wherein the rutheniumcompound in the gas phase material preferentially deposits on thereceptor material as compared to the at least two electrodes.